Sunspots are dark spots on the surface of the sun, resulting from storms that cause significant magnetic activity, the release of gases and solar flares. It is believed that the level of this solar activity is cyclic, repeating on average every 11 years. Whilst increases in the sun's activity does impact the level of solar radiation received by earth, the impact of this on climate change is thought to be minor compared with the emission of greenhouse gases from human activities.
The Maunder Minimum, or 'Little Ice Age' that occurred between 1645 and 1715 has been attributed to a reduction in the number of sunspots, showing evidence of the level of solar activity and changes to the climate. However, no long-term trend of increased solar activity has been linked to the current increases in global warming (some studies suggest solar radiation has fallen over the last 30 years or so), suggesting that such warming is being principally driven by other factors.
